Study: 25 Percent of Cars Spew 90-Plus Percent of Pollution

A new traffic study found that roughly 25 percent of cars accounted for over 90 percent of pollution.

NBC News reported that researchers at the University of Toronto in Canada examined the emissions of 100,000 vehicles driving down College Street to make their finding.

"As we looked at the exhaust coming out of individual vehicles, we saw so many variations. How you drive, hard acceleration, age of the vehicle, how the car is maintained — these are things we can influence that can all have an effect on pollution," said one study author, Greg Evans.

The results were stunning.

Evans and fellow researchers discovered that just a quarter of the cars on the road generated 95 percent of black carbon soot, 93 percent of carbon monoxide, and 76 percent of volatile organic compounds such as benzene, toluene, ethylbenzene, and xylenes — some of which are known carcinogens.

"The ultrafine particles are particularly troubling," said Evans. "Because they are over 1,000 times smaller than the width of a human hair, they have a greater ability to penetrate deeper within the lung and travel in the body."

The discovery could be seen as good news, as the worst offenders were a narrow group, and methods of reducing emissions could in the future be more targeted at groups like these.

In addition to the discovery about the cause of roadway emissions, the researchers also discovered that vehicle pollutants were still highly concentrated over 900 feet downwind from their respective tailpipes, AutoBlog.com reported. Previous research had suggested pollutants where more significantly dissipated after 300 feet.